Medical devices involving fluid flow typically include a fluid flow path for a disinfectant operation such as a chemical disinfection. A hemodialysis device can function in place of a kidney by filtering waste, salt, and fluid from a patient's blood when the patient's kidneys do not function properly. To ensure the flow paths are properly disinfected for patient use, a chemical wash flows a disinfectant through the flow path. It is extremely critical that hemodialysis devices do not permit contamination of a chemical wash into a flow path containing fluid that may interact with a patient.
During a dialysis operation, a valve in a spent dialysate circuit is always closed, thereby preventing any potential contamination from the spent dialysate to the fresh water inlet. Additionally, an airgap between a water inlet valve and a hydrochamber prevents any patient contamination if there is an external loss of water pressure.
During a chemical disinfection operation, a valve is opened so that a chemical disinfectant flows from the spent dialysate side to the hydrochamber. A drain valve opens at a periodic time interval to disinfect the drain line, and fresh water flows through the water inlet valve to replace the volume emptied out the drain valve. During normal operation, the water circuit is under positive pressure, so water flows into the water inlet valve, and disinfectant is prevented from backflowing through the water inlet valve.
If an external water source fails, the water is no longer under positive pressure, and the chemical disinfectant has a path for potential backflow through the water inlet valve. Although risk to the patient is remote, a solution is needed to prevent potential backflow contamination to ensure patient safety.
It is with respect to these and other considerations that the present improvements may be useful.